1. Field of the Invention
The present invention relates to a brazing or soldering material and a production method thereof More particularly the present invention relates to a brazing or soldering material suitable for use in bonding a lead frame or the like, and a production method thereof
2. Description of the Related Art
A brazing material is used for bonding base materials by heat-melting a metal or an alloy having a melting point lower than that of the base materials to fill the gap between the base materials with the brazing material. Particularly, the brazing material permits bonding of complicated fine parts and bonding of different metals, has little influence on base materials, and is thus widely used for electronic apparatus. Of such brazing or soldering materials, solder frequently contains tin and lead as main components, and is frequently used for bonding a lead frame of an electronic apparatus which is required to have electrical conductivity. For solder, generally, consideration is mainly given to electrical conductivity rather than strength, and particularly solder is required to have high solderability for base materials.
In soldering, solderability is significantly affected by an oxide film on the surface of a base material. Japanese Patent Unexamined Publication No. 5-304235 discloses that solderability deteriorates due to an NiO.sub.2 film on the surface of a nickel-plated lead frame, Japanese Patent Unexamined Publication No. 7-164136 discloses deterioration in solderability due to an oxide film during brazing of aluminum, and Japanese Patent Application No. 2527278 discloses that solderability deteriorates due to tin oxide on the surface of a material to be soldered. In these publications, as improving means, the bonded surfaces of base materials, i.e., materials to be bonded, are modified.
However, surface treatment of the base materials is performed for a lead frame or the like which has already been incorporated into a circuit board, and thus circuits and a package thereof must be subjected to modification treatment. There is thus the drawback that in treatment under the condition of high temperature, for example, in plasma processing or the like, various equipment loads such as a measure for preventing damage to a circuit element, etc. are significantly increased.
In addition, although a flux is used for removing an oxide film from a base material, even when a non-corrosion type flux is used for bonding a lead of an electronic apparatus, a problem occurs in which peripheral device materials area are contaminated by coating the flux.
Further, since a flux must be coated before the soldering step, the process is limited.
Although, in some examples, a hydrogen-containing flux is used for soldering, it is necessary to wash out the residual flux after soldering. In some cases, the residual flux is not washed out after soldering. However, in such cases, a flux containing a small amount of halogen is used to sacrifice the solderability, or a flux containing a large amount of halogen is used for maintaining solderability, thereby causing the probability of generating migration due to the halogen component in the residual flux.